This invention relates generally to paperboard containers, and more particularly to novel side panel construction to facilitate proper alignment and adhesion on assembly of such containers.
In the paperboard carton art, there are machines for folding carton blanks with the contents enclosed upon completion of the folding operation. One such carton blank folding machine is disclosed in U.S. Pat. No. 3,665,675 owned by the assignee of the instant application, and entitled "PACKAGING MACHINE." The folding operation described in said patent refers to a manufacturer's lap or flap of the carton blank being required to be secured to form the manufacturer's joint of the assembled container. Also, certain flaps disposed opposite to and spaced from the manufacturer's joint must be secured. This folding or wrap around operation requires mating panels or flaps of the carton blank to be pressed against one another and held in face-to-face juxtaposition by suitable pressure until adhesive applied therebetween sets or dries.
A problem which occurs during setup of such a carton blank in a carton folding machine arises in connection with completing said manufacturer's joint satisfactorily because the adhesive must set to maintain the joint. One solution to this problem is shown in U.S. Pat. No. 3,744,705 owned by the assignee of the instant application, and entitled "CARTON CLOSURE RIGIDIFYING CONSTRUCTION" This patent described an improved manufacturer's flap having slot and tab means provided between the juxtaposed top and front panels to maintain the manufacturer's joint rigid and intact while the adhesive sets.
However, the slot and tab means did not fully solve the problem encountered in connection with the positioning and maintaining pressure with the aforementioned flaps which are spaced apart from the joint. It has been found that either regular or tapered cutting of the outer flaps of the container, which is necessary to permit stripping of the slots in a carton folding machine, causes a further problem. When using a full or partial overlap configuration in the containers, it has been found that the tapered or regular slots cause a concave effect on the adhesion characteristics of the mating panels or flaps of the carton blank. When the products to be enclosed do not totally fill the container, the inner flaps have minimal or no support to provide pressure against the overlapping outer flaps so that the joint may adhere properly. This results in an adhesion which is satisfactory only at the points closest to the inner flap scores and containers which are misaligned and insecure. This is especially pertinent and relevant in high-speed carton folding machines.